FIG 1.

Infectivity of influenza viruses in human lung epithelial or endothelial cells. Calu-3 cells grown on transwell membranes or HULECs grown on chamber slides were infected with influenza virus at an MOI of 1 for 1 h. Cells were fixed and stained for influenza virus NP (green) or DAPI (insets, blue) at 8 h p.i. (A) Immunofluorescent staining of virus-infected cells. The confluent cell monolayers are shown as insets at the top right corners. (B) Assessment of infection rate in virus-infected cells. NP-positive cells and total cells were counted at a higher magnification (×400) for calculation of infection rate (number of NP-positive cells/number of total cells). Values represent the means of four independent areas, with the standard deviations indicated. An asterisk indicates a statistically significant difference between groups (P < 0.05).